1 |
Influences of phase transformations on the pitting corrosion behavior of wrought duplex stainless steel in different environmentsKuan, Hong Cheng January 2018 (has links)
University of Macau / Faculty of Science and Technology. / Department of Electromechanical Engineering
|
2 |
Corrosion of stainless steels in bulk and under thin layers of electrolytesBasman, Alexander R, University of Western Sydney, Nepean, Faculty of Science and Technology January 1993 (has links)
Passivation, local anodic depassivation and pitting corrosion of stainless steels in bulk and under thin phase layers of acid sulphate and neutral chloride solutions have been studied. A number of electrochemical, chemical, metallographic and physical techniques were employed in this study. The choice of stainless steels, test solutions and methods of investigations was based on scientific expediency and practical availability. For the first time in electrochemical and corrosion characteristics of passivation, local anodic depassivation and pitting corrosion of stainless steels were obtained in thin layers and compared with those in bulk electrolytes. It was demonstrated that the thickness of the electrolyte layer can influence the passivation process and, under certain conditions, the kinetics of pitting erosion. Several tests were conducted and results given. It was shown that the prognosis of corrosion behaviour of some stainless steels in sulphur dioxide contaminated atmosphere based on electrochemical measurements in bulk electrolytes can be erroneous. The same measurements carried out in thin phase layers enable more accurate prediction. However, the prognosis of the relative resistance of the stainless steels to pitting corrosion in the clean chloride-containing atmosphere may be based on conventional electrochemical measurements in the bulk of corresponding electrolytes / Doctor of Philosophy (PhD)
|
3 |
EFFECT OF FISSION PRODUCT ATTACK ON THE MECHANICAL PROPERTIES OF FUEL CLADDING ALLOYSRosa-Gonzalez, Ferdinand, 1940- January 1974 (has links)
No description available.
|
4 |
The environmentally assisted cracking of ru enriched laser alloyed surface layers on 304 L stainless steelTshilwane, Nick Nonofo January 2018 (has links)
A dissertation submitted to the Faculty of Engineering, University of the
Witwatersrand, Johannesburg, in fulfillment of the requirements for the
degree of Master of Science in Engineering
Johannesburg, 2018 / The use of austenitic stainless steels in harsh environments at elevated temperatures
has increasingly become a global problem, these alloys can fail unpredictably when
subjected to tensile stresses and chlorides. Hence the study was focused on
understanding the environmentally assisted cracking of Ru enriched laser alloyed layers on
304L stainless steel in a corrosive environment at elevated temperatures. The Ru
composition of laser alloyed samples was 0, 0.96, 1.96, 4.74 and 9.2 wt%.
Microstructural analysis and microhardness measurements were performed in order to
understand the grain orientation and resistance to indentation respectively. The bend beam
SCC test was conducted by stressing the samples to 350 MPa and exposing them to 50 ppm
sodium chloride with 10 ppm dissolved oxygen at 160°C for 172 hours. The results revealed
a significant improvement in the SCC resistance. The samples with lower Ru content (0,
0.98 and 1.96 wt%) were less susceptible to SCC when compared to as-received 304L
stainless steel. Cracks initiated from pits and propagated transgranularly on the alloyed layer.
The crack growth rate decreased as the Ru content was increased. The samples with 4.74 and
9.2 wt% Ru were immune to SCC. Electrochemical test results showed improved corrosion
resistance when the Ru level was increased to 1.96 wt%. Thereafter, there was a
gradual increase in corrosion rates for samples with 4.74 and 9.2 wt% Ru. However, these
corrosion rates were lower when compared to as-received 304L stainless steel. Another
SCC test was conducted to investigate fractography of vacuum remelted samples alloyed
with Ru. The results showed ductile failure for most of the samples and the maximum
stress threshold of 580 MPa was archived on samples with 1.07 wt% Ru. There was a
sudden increase in failure time, % elongation and % reduction in area when the Ru content
was increased to 1.07 wt%.
In essence, laser surface alloying 304L stainless steel with higher Ru content (more than
2wt%) improves SCC resistance, but does not improve the general corrosion
resistance, therefore a careful selection for any application is necessary. However, the
cost analysis revealed the laser surface alloying of 304L stainless steel with Ru to be more
efficient over other corrosion resistant materials. / MT 2018
|
5 |
Effects of metallurgical variables on the cavitation erosion behaviour of wrought austenitic stainless steelWang, Kai Yuan January 2017 (has links)
University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering
|
6 |
Effects of metallurgical variables on the cavitation erosion behaviour of AISI 304 austenitic stainless steelLi, Jing Hui, January 2017 (has links)
University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering
|
7 |
Effect of substitution of deuterium for hydrogen in water on the electrochemical kinetics of stainless steel - 304Kaul, Shiv Nath. January 1965 (has links)
Call number: LD2668 .T4 1965 K21 / Master of Science
|
8 |
Computer models of corrosion in passivating systemsPhillips, Simon Sebastian January 1995 (has links)
Analysis of corrosion in marine and acid environments is a complicated task, involving the interaction of thermodynamic, kinetic and geometrical factors. Two mathematical models which predict corrosion behaviour have been implemented for personal computers. The first program uses an assumption of unidirectional current flow to simplify the prediction of potential distributions for systems of essentially cylindrical geometry containing natural seawater-based electrolytes of differing strength. Using experimentally determined electrochemical and flow rig data, experimental and theoretical results were compared. The correlation between the two was shown to be poor, and this is attributed to the unrepresentative nature of the electrochemical data input to the model. The second model involves the synthesis of polarization curves. Several algorithms to model passivating behaviour have been studied, and one was selected and incorporated into the calculation routine. A number of kinetic and thermodynamic parameters are used in algorithms describing such behaviour, along with activation, concentration and solution polarization effects, for a number of redox reactions, which are then combined to produce an overall potential-log current density curve. Experimentally determined data for pure iron and different stainless steels in marine and acid environments of differing dissolved oxygen content and temperature were obtained. Theoretical models were constructed for each system, and compared to experimental data. Excellent correlation between experimental and theoretical data was obtained for potential ranges in excess of 2 V. Trends in parameter values were discussed, and compared to published data. The transition between stable and unstable passivity of stainless steels was shown to be dependent on the oxygen reduction diffusion limited current density and the iron dissolution reaction free corrosion current density, which in turn was linked to the dissolved oxygen content and temperature of the electrolyte. A new model for the behaviour of stainless steels in the transpassive region was proposed.
|
9 |
Electrochemical corrosion behaviour and inhibition of metallic alloys in acidic environments.Loto, Tolulope Roland. January 2014 (has links)
D. Tech. Chemical, Metallurgical and Materials Engineering / Corrosion is the chemical or electrochemical interaction between a material, especially metals, and their environment resulting in mild to severe deterioration of the material and its properties. The economic impact and problems resulting from corrosion has drawn strong attention from scientists and engineers worldwide. Stainless steel is the most important engineering metal worldwide, and industrially stainless steel is used extensively due to its resistance to corrosion e.g. in acid pickling, industrial acid cleaning, acid descaling, oil well acidizing and the petroleum industry. The corrosion resistance of stainless steels is due to the formation of a protective film which covers the steel surface instantaneously when exposed to mild operational conditions in the presence of oxygen; however, the oxide is most often porous and insufficient to protect the steel from further oxidation and corrosion attack in harsh environments. It is hypothesized that: In-depth understanding of the electrochemical behaviour of ferrous alloys in interaction with selected organic compounds in acidic environments will enhance inhibitor application for corrosion control; Failure and poor performance of most inhibitor admixtures can be eliminated with comprehensive knowledge of electrochemical interaction at the metal-inhibitor interface, passive film formation, duration and breakdown, adsorption characteristics, bond formation and molecular structure effect; Optimization of the current electroanalytical method will enhance effective pitting corrosion detection, analysis and control with the use of organic inhibiting compounds. The primary aim of this research is to develop the science required for the effective assessment, development and confident use of organic compounds (heterocyclic compound, organosulphur compound, simple alcohol, aromatic amine compound, aromatic amine derivative and aminoalcohol) and tested alloys (austenitic stainless steel type 304 and mild steel) for applications in astringent environments through conventional and optimized corrosion monitoring techniques.
|
10 |
Influence of surface roughness on the pitting corrosion behaviors of stainless steels in different environmentsCheong, Kim Hong January 2017 (has links)
University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering
|
Page generated in 0.1101 seconds